


Where Nightshade Blooms

by Ocean_inthe_Sun



Category: Fire Emblem Series, Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Action/Adventure, Canon-Typical Violence, Character Death, Eventual Relationships, F/M, Magic, Multi, Other Additional Tags to Be Added, Polygamy, Post-Timeskip (Fire Emblem: Three Houses), Pre-Time Skip, Two Byleths
Language: English
Status: In-Progress
Published: 2019-08-07
Updated: 2019-08-08
Packaged: 2020-08-11 15:02:25
Rating: Not Rated
Warnings: Graphic Depictions Of Violence
Chapters: 2
Words: 4,428
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20155528
Author URL: https://archiveofourown.org/users/Ocean_inthe_Sun/pseuds/Ocean_inthe_Sun
Summary: Twin Mercenaries Byleth and Bylara have developed quite the reputation, perfecting their exceptional skills on the road, alongside their father and his band of sellswords. But a chance encounter with three young nobles leads to a new life at the famous Garreg Mach Monastery, where they become embroiled in tricky politics, faced with dangerous secrets, an array of colorful students, and ensnared in an unexpected destiny. It's nothing they can't rise above though. The goddess put the both of them together for a reason.





	1. Chapter 1

**Author's Note:**

> I recently finished my first playthrough of this game, am now simultaneously doing a second and third, and I just really felt inspired to write for it. I sat and mulled over plots until I found one I thought was worth putting out there. In this M!Byleth AND FM!Byleth are in play. M!Byleth is the one with the quieter, harder to read personality that is the default in the game. FM!Byleth wears her heart on her sleeve a little more, as twins with identical stoic personalities is a bit too horror movie-esque if you ask me.
> 
> So you can imagine how that shakes things up some. And I know the mystery surrounding Byleth's age is sort of deliberated on a lot in the game but for the sake of where I'm going with this, Jeralt was telling the truth when he said he had a child (children in this case) years after leaving the Church. So the Byleth's are 17 pre-timeskip. The romance is gradual/slow burn and yes I'm thinking to indulge the fact that I wish the series did, there will be polygamy down the line. But the two Byleths probably won't share love interests. Character development and plot come first though.

The ground was muddy and trodden, not even the smallest blade of grass poking through as thousands of booted feet marched across the great expanse to meet their adversaries. Steel sang through the valley as men fell from horses and others faced their end from the tip of a spear.

The whinnies of pegasi maneuvering around arrow projectiles as their riders fought joined the cacophony of noise. The size and intensity of the battle was at once horrifying and awe-inspiring, a once in a lifetime sight.

Through it all, a weapon glowing hotter than coal pierced the dark, smoke-charred sky, preceding the arrival of its fearsome owner. A grizzled man in pieces of armor, dirt marring his leathery skin, landed with a thud.

Dazed, enemy troops gave him a wide berth before regaining their mettle and charging forward to close the gap. The warrior rose, lashing out with his strange blade. Red light shone like the magic of a mage’s spell, and where the segments of the blade traveled, soldiers fell. Through the path of the opponents he had felled, a woman stood, so poised and beautiful she looked terribly out of place amid the chaos and death on the field.

He charged at her, not batting an eye as a soldier fell at her feet, her name falling from his tongue as he perished.

She drew her blade and held it ready, pale green eyes flinty, her full lips pulled in a small scowl. With heavy feet he ran for her, cutting down the men brave enough to try to intercept him. Dawn broke as their eyes met, warm sunlight falling over them, somehow only making both appear more ominous.

Their single combat was a series of furious blows, neither gaining the true upper hand as they met in a shower of sparks with each heavy swing of their weapons. The fact that they were evenly matched drove their rages, until the man began to drive the lady warrior back, causing her to lose ground rapidly. Snarling, he flicked his blade, the orange sword splitting apart as it flew towards his winded adversary. She slid to the side in the last moment and instead of piercing her stomach, the sword snapped her belt. Another flick and he had wrapped the coils of his weapon around the shaft of her own.

She tossed her blade aside, and his, still coiled around it, came with it. Off guard, he had no recourse as she ran for him, delivering a punishing blow to his jaw and then leaping to smash both feet into his chest, bringing him to the ground. Scrambling to sit up proved a bad move when she brought a foot slamming down on his chest. Her blade followed soon after, and she leaned down into his face, beautiful and deadly.

“Tell me Nemesis, do you recall the Red Canyon?” she breathed through clenched teeth. His gold eye widened, recognition briefly flickering through it. “You die for that!” Her blade drove through him with a squelch. “Die!” He groaned, beginning to choke blood. “Die!”

Another stab. Sunrise broke on the battlefield, illuminating the body of the nearly-dead man underneath her, and her face pinched in pain. “You took…everything I loved!” The final strike held the most vehemence, cutting the death rattle short. Panting hard, she came back to herself to see both armies were only watching them. Finally, cheers and raised banners signaled the end of the battle, and her mint leaf hair fell over her shoulders as she turned solemn eyes to the blade her opponent had left behind. Delicately cradling it to her face, heedless of the crimson still staining it, she sighed. “He’s gone now, Mother.” she promised.

* * *

Light and sprinkles of color warped the image of the quieting battlefield, flashing fragments in fractured hues sucked at the edges of the scene.

“Hey. Time to wake up.” A gruff but caring voice, one so familiar it was recognizable to them anywhere. No longer on that battlefield, but in camp, where their father and other mercenaries were cleaning up and preparing breakfast. 

Groggy, Bylara cracked her eyes open, her vision blurry with sleep but still able to mostly make out the form of the person on the bedroll beside hers. His midnight blue mop of hair, the exact color of her own, fell into his peaceful face. “Brother,” she smacked at his arm. “Morning.”

Between the two of them, she had always been the lighter sleeper, and so it was no surprise when her twin merely turned his back to her and slumbered on.

Her eyes narrowed. _‘Is that the game?’ _ She was very familiar with her brother’s sleeping habits, rolling to pounce onto him, and unsurprised when his reflexes kicked in and he pinned her with a grunt.

“This game grows old…” he muttered, eyes half-lidded.

Their arms grappled, keeping him from pressing his full weight onto her.

“So does your oversleeping!” she returned, tossing him away from her and watching his larger body roll across the ground until he stopped on the grass, eyes to the sky…and right at their father’s feet.

Jeralt sighed, hands on his hips. His dark eyes swept over them. They didn’t look a thing like their father, who still had his butternut hair and beard without a streak of gray. Bylara and Byleth had come to the conclusion that they must both get their coloring from their mother.

Their mercenary skills, though, were entirely from Jeralt. He’d taught them all they knew, and even now they still learned watching how efficiently he could cut a line through a wave of enemies. There was no sign of him slowing down soon. In fact, aside from the lines carved around his mouth and eyes and the few, thin scars, there were very few indicators of his age, and it was a mystery they had long since stopped pondering on. 

“What exactly am I supposed to do with the two of you?”

Byleth sat up, running a hand through his hair to dislodge any blades of grass.

Bylara sat cross-legged, turning her nose up. “Teach your son that a mercenary who sleeps deeply is asking to be gutted.”

Byleth’s eyes lazily drifted her way. “I would wager you only woke up slightly before me…”

“Alright, alright,” Jeralt groaned. “Sorry I asked. You never do get tired of antagonizing each other, do you?” Even as he spoke, a barely-there smile was on his lips.

Byleth rose and stretched, arms straight above his head as his back popped. Bylara stood with her legs shoulder-width apart and leaned to the side in a stretch. First the left arm above the head, then the right.

“Any unusual dreams to report?”

“I dreamt about a battle unlike anything imaginable…Thousands and thousands of soldiers fighting in a big empty valley.” Bylara found herself saying absently. “And the sword…”

“I dreamt of a girl with green hair on a throne.” Byleth stated.

As always, their father met their words with a concerned furrow of the brow. “If it’s the same battle you’ve been dreaming of all this time, then I have to say I’m at a loss. I haven’t heard of a battle of that magnitude happening since the war nearly three hundred years ago.” He turned to Byleth. “And your mystery girl…you’ve described her to me before. I still don’t think I’ve ever met anyone like that.”

Byleth’s face didn’t move, but she could tell he was still in deep thought. Their father could too; he was too adapt at seeing right through the both of them. “In any case, just put that out of your minds for now. The battlefield is no place for idle thoughts,” They nodded slowly in agreement. Jeralt began to walk camp and they followed, “Risking your life is part of the job for mercenaries like us. Letting your mind wander is a sure way to get yourself killed.” 

Bylara didn’t need to look to know her brother was staring straight at her now. How rude. So she was prone to daydreaming from time to time. It had still been _her _that once saved _him _from an out of control Pegasus while he was off in his own world.

“Ok, time to get moving. Our next job is in the Kingdom.” Stopping short, Bylara stared at her father’s back in silent surprise. The Kingdom? That far? Just as quiet, Byleth was considering their destination too.

“I told you before, it’s far from here. So we’ll need to leave at dawn.” Jeralt continued.

“Of course.” Byleth said, smoothly.

“Uh, sure…” Bylara nodded.

“Hm?” Jeralt glanced over his shoulder. “Good grief. Everyone is already waiting around for us.”

The twins bowed shallowly. “Sorry…” they muttered.

“Just…” He rubbed at the back of his head, right above his short braid. “Byleth you can make sure the horses are all ready for the trip. Bylara, why don’t you go down to the river and fill up all the canteens. It’ll probably be a hot one today. I’ll go make sure there’s something left for you to have breakfast on the road.”

All in agreement, they set to work on their respective tasks. Bylara passed their bedrolls and packed them up, then took the canteens for the short trek to the river nearby.

Meandering through camp, she got plenty of smiles and greetings from various members of their party. These men had seen her and her brother grow up, watched them become the fearsome Ashen Demon Duo they were today.

Bylara hummed to herself, a tune she wasn’t quite sure where she picked up, coming to the last copse of trees that separated the camp from the riverside. The birds were starting up their daily songs, and the crisp grass underneath her feet smelled ripe in the April sun.

Careful to avoid rocks, she crouched by the calm river and uncapped the first container. It didn’t take long to fill, and she replaced the top and set it on the bank beside her, reaching for another. Bylara had just finished unscrewing that canteen with steady hands, when the trees rustled and hurried footsteps reached her ears.

She’d think nothing of it normally. After all, they had made camp with plenty of other people. But the short pants that accompanied the quick pace was worrisome. Abandoning the canteen, she got to her feet, giving the forest an eagle-eyed glance.

There! She gasped. Someone was definitely running closer. One minute she thought she saw a flash to her right, then her left. Whirling around in a circle, she reached for the blade at her hip, thankful that her father had drilled caution into them. Even with a quick trip to the river, the tides could swiftly turn.

“Show yourself.” She demanded, not expecting for the declaration to be followed by her on the ground and wheezing moments later.

Some yellow flash had collided with her, the sturdy weight of a warm body pushing her flat on her back. “Well hey there,” a boy grinned down at her, the small braid at the side of his face tickling her throat as he sat up. “Don’t mind if I drop in, do you?”

Bylara studied his playful green eyes, tanned skin, and the messy style of his short, dark hair. She’d never seen this character around the campsite or the village just beyond it before. Managing to wiggle her arm free, she took up the sword she’d dropped and tapped him lightly, careful of the tip. “Get off.”

He obliged, even helping her onto her feet without waiting for permission. “Yeah, sorry about that. Not my best entrance. But kind of in a hurry,” He glanced behind him and frowned. Curiosity overcoming her aggravation, Bylara followed his eyes. “I’ve been separated from my traveling party, and now it looks like my friends too. We got chased by some bandits that saw our clothes and decided we’d make good targets.”

Bylara took the chance to appraise him, noticing for the first time that while he was indeed wearing a short yellow piece of fabric that tucked into his shirt and rested over his shoulder, his sleek black uniform was far too striking to belong to anyone other than a person of high standing. Too young to be an official, but maybe a noble? But his blasé attitude…

“Think you and your party might be able to lend a hand?” Again his demeanor was so casual. So unlike what she’d expect from a noble. “Well, you know, assuming you’ve got one.”

“I have one.” she said. “They’re just up ahead. And if you and your friends are so valuable to them that they’re chasing you down, then the village near here could be in trouble.”

“I wouldn’t doubt it,” he shrugged. “The bandit’s leader seemed like an unhinged, relentless guy. Not the type that would lose sleep over hurting whoever got in his way.”

Bylara shook her head, already starting to jog away from the bank. “Let’s go regroup with my party. Maybe your friends have already found my father and the others.”

When she glanced to her side, she noticed that not only was he easily following, but now holding a simple bow at the ready, the quiver of arrows on his back noticeable for the first time.

At least she wasn’t dealing with someone who was totally defenseless.


	2. Chapter 2

**Summary for the Chapter:**

> Defending a mysterious trio who beg for help leads to a skirmish, but more significantly, a once in a lifetime meeting.

The horses were raring to go. Fed and watered, they swatted their tails and stamped the ground gently, sensing another day of traveling ahead. Byleth offered up some hay to a tan mare who had been recovering from a minor hind leg injury sustained in battle, and she nibbled it gratefully.

Satisfied, he let his thoughts wonder to the next assignment. Anything could be waiting for them in the Kingdom. The life of a mercenary was often unpredictable as well as perilous. His father was right. Wandering thoughts were a good way to get hurt or worse.

And yet…the dream seemed so real, the image of the girl he’d spoken to, who had asked him his name and told him they shared a birthday, was as vivid as a fond memory.

He should probably be more concerned about what it all meant, and if he were in danger of losing his sanity, but Bylara was just as adamant about the dreams she had of war lately, and that made him feel less concerned over it. His sister had always succeeded in making him feel more at ease by merit of the fact that she was right there with him.

From the time he was small, Byleth could remember how people would remark to Jeralt that his son was an odd one. In towns they traveled through, Bylara was usually the one invited to join in games with the village children, and would persuade them to include him. He didn’t doubt he was peculiar, if almost everyone said he was. But at least his sister had never minded.

Byleth patted at the mare’s neck in farewell, knowing it was time to tell Jeralt preparations were complete. As he’d said, they had already kept everyone waiting. But when he wandered away from where the animals were kept tied to posts, he noticed urgency had descended over the camp in the short time he was preoccupied.

When a newer member of their band rushed by, Byleth caught him by the elbow. “What is it?”

The man whose name he thought he remembered as Dalton, stared up at him with wide eyes, then shook his head. “There’s been a disturbance. Some travelers have been attacked by a powerful group of bandits who are in pursuit. We’re meant to meet them when they come from the east and cut them off before they can attack the village.”

Byleth instinctively reached for the sword safely sheathed at his hip, eyes narrowed. “And Jeralt?”

“Over there!” he pointed a shaky finger off in the distance and Byleth could just barely make out his father’s orange jerkin, as he stood beside what appeared to be a young man and woman.

Letting Dalton go, he sprinted past mercenaries now armed to the teeth, his solid footsteps alerting Jeralt and the others.

His father didn’t waste time. “I take it you heard?”

Byleth gave a single nod. “Bandits out for blood. Keep them away from Remire Village.”

“And protect these two,” he motioned at the boy and girl who must have been right in the middle of the commotion.

“We thank you in advance for your aid,” the young woman said, her voice clear and confident. Her lavender eyes appraised him openly, and he did the same, taking in her long silvery hair, the fancy black blazer and matching skirt complimented by the short red fabric draped over her right shoulder. She had such a regal bearing, so delicate and feminine at a glance. But, she clutched a battle axe like she knew how to use it. Catching where his eyes had traveled, she raised her weapon to hold over her shoulder. “You’ll find we’re capable of helping as well.”

“Yes,” The boy with her was lean, blonde and equipped with a well-polished lance. “You’re defending us even though we’ve barged into your camp unexpectedly. Assisting is the least we can do.” he sighed, his blue eyes turning downward. “Though I’m a bit worried for our friend. He ran first as a decoy, you see—”

“So you guys found help too, huh?”

The group looked over to see Bylara and another unfamiliar young man jogging up to them. While his sister was already on her guard with sword out, the yellow-clad stranger radiated laxness.

“Claude!” His friends gasped.

“What a relief.” The girl began, “Going off on your own like that…we feared the bandits would catch up to you before we did.”

The sun-kissed boy, Claude, held his arms out, a bow gripped in one hand. “As you can see, I’m all in one piece. I even managed to make a new friend as a matter of fact.”

Bylara closed her eyes and said nothing, a sign that she didn’t deem his statement worth refuting.

“You’ll have to save the reunion for another time,” Jeralt grunted. “Looks like they’re here.”

Sure enough, a burly man in leather and furs charged from the woods leading a large group of rowdy fighters, roaring their battle cry.

“Gimme those rich brats!” The leader snarled, zeroing in on Claude and his friends.

“Here we go.” Byleth and Bylara turned to their father, seeing another member of the party approach with the reins of a saddled horse in hand. Jeralt climbed atop the creature, a strong chestnut steed he had rode for the past five years. “I’m putting you two in charge of commands. I don’t have to remind you to take this seriously.”

“Yes!”

“Let’s go,” Bylara murmured. “I’m guessing that’s not just for show,” she gestured at the bow in Claude’s hands. “So we’ll start by having you shoot first.”

Claude deftly flipped an arrow between his fingers before notching it in no time flat. “Sure, just say the word.”

Byleth found himself sizing the boy up again. Being raised the way they were, these situations of rescuing people from bloodthirsty brigands was nothing new. He had no idea what the trio’s background was like, but Claude’s approach to a life and death situation was certainly...calm. 

“Aim for him first,” his sister commanded, gesturing at the first ruffian to weave through the mercenary’s defenses, who was coming at them fast.

Claude fired without question, toppling the man with an arrow to the thigh. Byleth rushed in, cutting him down dead before he could jerk the arrow free.

“Nice,” the archer praised. “I think we might be in capable hands here.” He called, looking in the direction of the two clad in blue and red respectively.

“Yes, but stay focused, Claude. That’s not even the first wave.” The girl scolded.

“The forest!” Jeralt ran a second bandit through so fast the man was bleeding out before he had time to see the wound.

“Right,” Byleth agreed. “We have a better chance of maintaining the advantage if we attack from the forest. Time to take positions.”

No one questioned the logic, their new allies following once again. They hid themselves among the trees at the edge of camp and listened as the brigand’s leader loudly cursed over losing sight of them.

“I must say you’re both adapt at thinking quickly,” The white-haired girl whispered. “I admire that kind of resourcefulness.”

“They’re coming this way,” The blonde pointed out. Through the foliage they could see a handful of enemies had fanned out to search for them while the others took on Jeralt and his mercenaries directly.

How pesky. But they weren’t in trouble yet. In fact…

“Ambush?” Bylara asked.

Byleth had never questioned how easily his sister and he shared their thoughts. “Ambush.”

When a scarred man missing half of one ear came cutting through the trees with his axe, Bylara popped out, using her Combat Art and dropping low. She stood and spun behind him, her blade swift as it flickered out, coming away red. Some blood dripped onto her boot, and she only spared it a passing glance, swallowing as she flicked the tip of her blade and pulled it away from the body.

“Incredible.” He heard one of the three behind him say.

“Huddle in close,” he told them, and they all complied, forming a tight triangular unit where he and Bylara took the front, the blonde and girl behind them, and Claude taking point.

It was just in time, because apparently the fallen bandit’s comrades had discovered their location, rushing over to try and overwhelm them. Bylara and Byleth fought the first wave, the other three following their lead.

When Byleth became distracted guarding his sister’s blind spot, the lavender-eyed girl used the reach of her axe to strike down a bandit who tried to take advantage, and he turned in time to see the man cough roughly before dropping to the ground.

Claude used his position from the back to hit opponents who had forgotten about the archer, covering them from the rear.

_‘Not bad.’_ Byleth thought. All three were holding their own well.

Bylara cried out when the man she’d been swordfighting moved away suddenly, throwing her off balance. She stumbled, momentum bringing her forward and in range of an unblocked attack.

Thankfully, the blonde intercepted the next blow with his lance, pushing the weapon away and allowing Bylara to get her bearings enough to stab the bandit while he was preoccupied. He fell back a step, arrow lodged through his heart soon after.

His sister quietly acknowledged the help of both boys by briefly looking them in the eyes. “Thanks,”

“Certainly,” the blonde responded. “I believe we’ve driven them back for now. But the leader remains at large.”

He was right. In all the fighting, the leader had managed to avoid coming into harm’s way while sending his underlings to face them. The saying went that there was no honor among thieves, and Byleth supposed that extended to brigands too.

“What?” Claude guffawed, lowering his bow. “Is he seriously gonna chase us down and swear to take our lives, then wait for us to confront him?”

“Father can take care of the others, but let’s go corner the head dastard and end all this.”

Byleth took the lead this time, passing Jeralt. Silent understanding passed between father and son, and confidence bloomed in his breast. Finding the leader wasn’t hard, as he stood in plain sight, barking orders and swinging a large axe. When he saw the five teenagers approaching him backed by some of Jeralt’s men, a wicked grin touched his cracked lips.

“Killing all of ya is gonna be the most rewarding hunt I’ve had in ages!”

For a bandit, he was formidable. A definitive cut above all the others they had already faced in the battle. But he and Bylara were known for being skilled beyond their years, and in the end he underestimated them a little too much.

He fell in the dirt, axe landing beside him. Stunned, his subordinates eased away.

“Are you three alright?” Byleth asked, feeling the throb of a wound to his shoulder. Superficial. With some basic healing magic it would be good as new.

The boy in the blue cape wiped sweat from his brow and smiled politely, awe swirling in the depths of his azure eyes. “Yes, due in no small part to you. I have witnessed it with my own eyes, and yet it is still hard to believe you are ordinary mercenaries when you possess such advanced skills.”

Claude came up behind his friend, flinging an arm around his shoulder and leaning forward. “Gotta agree with His Princeliness here. The two of you look like you’re the same age as us, but what we saw out there,” He finished with an impressed whistle.

The soft crunch of heels had Byleth turning to see the red-clad girl had just set her axe down and was walking over. “You both have strange auras about you,” she noted, curiosity flickering behind her expression. “And you commanded us well on the battlefield.”

Slowly, her lips pulled into a soft smile. He was familiar enough with fleeting smiles, being that his own were closely guarded, to know when someone else seldom gave them. A small part of him felt compelled to return it. 

“Great work,” Jeralt rode over, staring down in approval. “You handled yourselves even better than expected out there. And I see our friends aren’t any worse for wear.”

“We only did what we always would.” Bylara responded, both to their father and the three young fighters. “Though, it’s nice that we were able to provide you backup.”

“I’d say it was the other way around,” Claude laughed, letting go of the lance-wielder. “I mean without you we’d be—”

“Damn it!” The roar was loud enough to make the blonde flinch. Without much warning, the downed brigand had surged to his feet, axe gripped tight, his face crazed as he went for the girl.

She was still weaponless, her own axe too far to reach in time. Byleth knew what he had to do, but it really came as no surprise when his sister happened on the same idea. They both threw themselves to defend her as the axe came down.

And then, quite literally, time stopped.

**Notes for the Chapter:**

> A M!Byleth POV this time~  
Well next chapter is the all important moment where the twins meet Sothis, and of course become better acquainted with the House Leaders.  
I wouldn't be opposed to trying to squeeze in one more update for the week, but in exchange, please drop some comments.

**Author's Note:**

> I know the game is still pretty much new and not that many entries exist yet but I'm still really excited and expecting a lot of fun writing this. You may notice that FM!Byleth gets a lot of the POV for a while and that's mainly because I always prefer writing female character POVs. Although when doing third-person writing ultimately I use alternating POVs to give the story a better sense of depth. So M!Byleth will be just as important and plenty of the other characters have voices in this as well. No worries. 
> 
> Although it's early, I really would appreciate people dropping some comments. Thanks.


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